While in the past the electrical systems of a vehicle were normally supplied with power by a single power source, typically a lead-acid battery disposed in the motor compartment, modern motor vehicles are also provided with much more complex electrical supply structures. The onboard electrical system may be composed of a plurality of partial electrical systems, for example, which operate at different voltage levels. A partial electrical system may also be provided with a plurality of different types of power sources. The term power source comprises all devices which may be used as a source of current and/or voltage for at least one partial electrical system.
Due to the increased complexity of such onboard electrical systems, it may happen, for example, that in case of repair and/or maintenance work, by detaching a determined power source, such as in particular a battery mounted in the motor compartment, it cannot be ensured that the entire electrical system is effectively voltage-free. An operator performing the repair or maintenance should initially study complex documents in order to find all power sources to be considered while working on the motor vehicle. In many cases the operator is however not informed about further power sources that may be mounted in the motor vehicle in addition to the first power source. Another drawback is found in such complex electrical systems in case of rescue operations, in which the rescue personnel usually wants to ensure the removal of voltage for their safety and the safety of third parties. To this end, it was proposed to provide so-called rescue maps available on the motor vehicle, in which the positions of individual energy storage systems on the motor vehicle are schematically represented.